“A president talks about principles, but a mayor collects the garbage” – Park Won-soon, mayor of Seoul, South Korea.

The importance of cities in tackling climate change is undeniable. They are responsible for most of the world’s people, money and greenhouse gas emissions.

Emerging cities of Asia and Africa, in particular, have an opportunity to choose energy efficient hi-rise blocks and public transport over suburban sprawl and motorways.

So what role can mayors play in the UN climate talks, which are due to reach a global deal in Paris this December?

It was a critical question for ICLEI, a network of local governments for sustainability, at its summit in Seoul last week.

“It is difficult for cities to play a strong role [in Paris], given that it is an intergovernmental negotiating process,” says Yvo de Boer, director general of the Global Green Growth Institute and former UN climate chief.

“At the same time I think there is a growing realisation that cities are not only a significant part of the problem of climate change, but also a significant part of the solution.

“As a consequence, I think there is a greater willingness to listen to cities.”

The clearest statement of intent to date is the Compact of Mayors, announced at UN chief Ban Ki-moon’s climate summit in New York last September.

Launched with 228 member cities, it signed up another 35 in Seoul. Signatories have three years to complete a climate action plan for their city and report their progress.

Ban’s summit was extra to the official UN climate negotiations and aimed to broaden participation in the climate agenda.

At the negotiations themselves, cities have historically been limited to holding side events. Paris mayor Anne Hidalgo has promised to amplify their voice at December’s talks.

Michel Rentenaar, climate envoy for the Netherlands, says cities’ involvement has been “too limited”. He wants to see cities submit text for the international agreement and publish their own emissions targets to complement national commitments.

Yet getting official acknowledgment of the role of sub-national governments has proved contentious.

Finance is another stumbling block. Cities remain highly dependent on funds from national government and ad hoc grants to fund climate-friendly infrastructure.

The World Bank estimates only 4% of the 500 biggest cities it works with in developing countries can attract credit on the international markets. One in five can raise money locally.

In Asia, the most rapidly urbanising part of the world, Amy Leung of the Asian Development Bank warns there is a big cash shortfall. Cities are spending US$40 billion a year, where US$100 billion is needed, she says.

There are new sources of finance coming into play, according to de Boer, and cities need to innovate.

For example, some lighting companies will install LED streetlights at no upfront cost, recouping the investment through the city’s energy bill savings.

Are cities going to get formal recognition in a Paris deal? Probably not. But that doesn’t mean they can’t influence the outcome.

If you think of greenhouse gas emissions as another form of garbage, mayors are the natural choice to mount a clean-up.